Return immediately if argument to BN_sub_word is zero.

ok markus@ deraadt@

2 files changed, 6 insertions, 0 deletions

diff --git a/src/lib/libcrypto/bn/bn_word.c b/src/lib/libcrypto/bn/bn_word.c
index ab858d70ff..de610ce54c 100644
--- a/src/lib/libcrypto/bn/bn_word.c
+++ b/src/lib/libcrypto/bn/bn_word.c
@@ -146,6 +146,9 @@ int BN_sub_word(BIGNUM *a, BN_ULONG w)
         {
         int i;
 
+        if ((w & BN_MASK2) == 0)
+                return(1);
+
         if (BN_is_zero(a) || a->neg)
                 {
                 a->neg=0;
diff --git a/src/lib/libssl/src/crypto/bn/bn_word.c b/src/lib/libssl/src/crypto/bn/bn_word.c
index ab858d70ff..de610ce54c 100644
--- a/src/lib/libssl/src/crypto/bn/bn_word.c
+++ b/src/lib/libssl/src/crypto/bn/bn_word.c
@@ -146,6 +146,9 @@ int BN_sub_word(BIGNUM *a, BN_ULONG w)
         {
         int i;
 
+        if ((w & BN_MASK2) == 0)
+                return(1);
+
         if (BN_is_zero(a) || a->neg)
                 {
                 a->neg=0;